Pipe joints or couplings – With casing – lining or protector – Insulated
Reexamination Certificate
2000-03-29
2001-09-11
Nicholson, Eric K. (Department: 3627)
Pipe joints or couplings
With casing, lining or protector
Insulated
C285S047000, C285S055000
Reexamination Certificate
active
06286875
ABSTRACT:
TECHNICAL FIELD
The present invention relates to gas line conduit systems and more particularly to an electrically insulated system which includes an integral union pipe as part of the system, which pipe is electrically insulated at one end for preventing the flow of electricity through the conduit to an earth ground. The invention further relates to the method of manufacture of such system.
DISCUSSION OF THE PRIOR ART
Gas lines of the type addressed by the teachings of this invention are well known as systems for bringing gas under pressure from underground delivery pipes into an establishment such as a residence or commercial structure, for utilization therein. For purposes of this specification “gas line” is intended to mean any conduit, pipe or similar-type enclosed passageway used to transfer gas under pressure. The gas may be used for any purpose, but most often is used for supplying heating energy, and it is common to utilize natural gas for this purpose.
The main gas line is generally buried underground, being brought in from the street or from any other source of supply. It often includes some form of metallic conduit which is capable of conducting electrical current. Once brought into the building, interior piping is utilized to plumb a system. The system might typically comprise a shutoff valve, pressure regulator, gas meter near the point of entry, and further conduits for delivering the gas to the various utilization devices.
Undesired electrical current may be generated in these supply systems from a variety of sources, such as for example, the flow of gas itself, which creates distributed electrical potentials. Electrical currents may also result from improper or defective wiring, and the like. Such current may then be transmitted through the interior conduits to the exterior underground line and create an undesirable condition. Such electrical discharges into the earth can create erosion of the supply line and its consequent failure prior to its otherwise predicted lifetime.
In the past, insulating fittings such as swivels and unions have been utilized that can be included in gas lines to provide an insulated connection between pipes that carry the combustible gas. Most often, these comprise a threaded coupling which has a union connection at one end which is covered or encapsulated in some manner with nonconductive material to interrupt the metal to metal connection and prevent the flow of electricity. While solving the electrical problem, such devices introduce another threaded joint into the system. Such a joint presents a potential leakage problem due to faulty installation, or more likely due to environmental conditions such as vibration, corrosion or damage by external forces.
Another form of insulated gas line conduit is shown in U.S. Pat. No. 5,588,682 in which a length of conduit may be provided with a threaded connection at one end and a flange at the other forming a flange for connection as a union with mating components. The flanged end of the conduit is covered with non-conductive material and serves to isolate the components to prevent conduction of electricity. In this arrangement, a pilot portion is formed at the end of the conduit to guide the conduit in its mating connection with the spud of a component to be connected. A relatively thin layer of non-conducting material thus covers the end of the conduit at the location where the prevention of conduction of electricity is desired.
Thus it may be seen that a need exists for a relatively inexpensive, reliable insulating coupling system for metal gas lines, which is not only easy to use and install, but also avoids unwanted electrical conduction and additional threaded connections.
SUMMARY OF THE INVENTION
The preferred exemplary coupling device and system of the present invention comprises an enclosed metal passageway suitable for transporting a pressurized gas. The passageway carries the gas to or from a gas meter. The system preferably comprises a conduit having a desired preformed configuration and having at one end portion a flange. An insulating resilient seal layer which is preferably a molded nylon piece, covers the flange end portion of the conduit, thereby electrically insulating the flange end portion. The system further has a threaded ring nut which can be moved over the conduit to engage the flange and further engage a component such as a shut off valve, which has a mating, flange-receiving, connector thereon.
In use, a threaded nipple, spud or other mating connector of a device having an outer thread is aligned with and pressed against the insulating resilient seal carried on the flanged end of the coupling. A ring nut is then moved over the conduit toward the spud until the open, threaded portion of the ring nut which extends beyond the flange, can be turned to engage the internal threads of the ring nut with the threads of the spud. As the nut is screwed onto the spud, the nut compresses the seal, and holds the flange and spud together, thereby tightly connecting and sealing the conduit to the spud. Thus the seal may act as both an insulator and a seal.
In the preferred embodiment of the invention, the gas carrying conduit which is to be insulated is a pipe nipple having a thread at one end and an enlarged flange at the other. The flange is machined into a preferred configuration and then encapsulated in an injection molding machine to provide an electrical non-conductive seal thereover. The seal is also of a predetermined configuration and includes not only a sealing portion of substantial thickness, but also an integral pilot portion. The pilot is a tubular extension of the seal beyond the flange on the nipple, and serves to center and guide the nipple and flange toward the sealing surface of the spud, by entering the bore of the spud upon makeup of the connection.
A ring nut which is placed over the nipple and slid along the length thereof into engagement with the flange, serves to complete the connection. Interior threads in the nut engage exterior threads of the spud and upon tightening, draw the pilot into the bore, and the flange toward the spud until a sealing engagement is effected. The arrangement of the flange and seal thereby provides surfaces which are engaged by the nut and which contact the spud to provide a non-metallic connection and thus insulation against the flow of electricity.
Preferably the flange at the end of the nipple is cold formed into an enlarged flange which is then suited for formation of specific surfaces for retention of the seal, for mechanical retention of the nipple with a mating component, and for the formation of a transverse annular sealing surface, which then serves as a union connection in the makeup of an entire conduit system. After cold forming, the flange is machined to a configuration comprising an inner annular ridge and an outer annular ridge, the two being joined by a central cylindrical section and a tapered or conical section. The central cylindrical section further includes a small intermediate ridge located near the inner ridge.
The outer ridge is machined to a diameter to substantially match the mating surface of a component to be joined, and has a flat, transverse face surrounding the bore of the nipple. Extending inwardly from the outer ridge is the conical section, joining the central cylindrical section at a diameter less than the diameter of the outer ridge. The central section extends inwardly to the inner ridge, the latter having a diameter greater than the central section and less than the outer ridge, and which serves as a limit for the seal material which will encapsulate the remainder of the outer flange. The intermediate ridge serves to enhance the grip of the seal.
The seal is comprised preferably of an elastomeric material such as nylon, and is joined to the nipple preferably in an injection molding operation. As such the nipple is placed in the molding machine and material extruded over the flange section to completely cover the end of the nipple, externally from the inner flange outwardly over the outer ridge
Snodgrass Larry R.
Williams Mark D.
Jocke Ralph E.
Nicholson Eric K.
Schuler Manufacturing Company
Walker & Jocke
Wasil Daniel D.
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